A vehicle, such as a hybrid vehicle, a plug-in hybrid vehicle, and an electric car, is provided with a high-voltage storage battery for power driving, an inverter device configured to perform power conversion of a DC high voltage output of the high-voltage storage battery into an AC high voltage output and drive a motor, a DC-DC converter apparatus configured to convert the DC high voltage output of the high-voltage storage battery into a DC low voltage output and perform power supply to a low voltage load such as a light or a radio of the vehicle, and a low-voltage storage battery as an auxiliary power source of the low voltage load being mounted thereon.
In general, the DC-DC converter apparatus is provided with a high-voltage switching circuit which converts a DC high voltage into an AC voltage, a transformer which insulates and converts the AC high voltage into an AC low voltage, a low-voltage rectifier circuit which converts the AC low voltage into a DC voltage, and an output terminal which outputs the voltage-converted voltage. The low-voltage rectifier circuit is provided with a choke coil and a smoothing capacitor element configured to smooth a DC output voltage. In addition, a filter circuit configured of a reactor and a capacitor is provided in order to reduce conduction noise to be output from the output terminal.
It has been desired to enhance the habitability in such a vehicle by increasing a proportion of an interior with respect to the entire capacity of the vehicle as much as possible. Thus, it has been desired to mount the inverter device or the DC-DC converter apparatus to a space, as small as possible, in an engine room or a trunk room other than a vehicle compartment, and the compact design is necessary. (For example, see PTL 1).